Three-layer breather valve composite diaphragm, its preparation method and application

Abstract

This invention relates to the field of breather valve sealing technology, and discloses a three-layer breather valve composite diaphragm, its preparation method, and its application. The composite diaphragm comprises a polymer sheet layer, a fluororubber composite material layer, and a fiber composite polymer interlayer located between the polymer sheet layer and the fluororubber composite material layer. The thickness of the polymer sheet layer is 0.1–1 mm. The fluororubber composite material layer is prepared from a raw material composition containing fluororubber, inorganic filler, acid absorber, vulcanizing agent, release agent, and colorant. The composite diaphragm provided by this invention has the following leakage rate at 20°C and 0.75 times the opening pressure of the breather valve in a storage tank: for a breather valve diaphragm with a nominal diameter of 150 mm, the maximum leakage rate is as low as 0.0010 m³ / hour. 3 The breather valve diaphragm, with a nominal diameter of 200mm, has a maximum leakage rate as low as 0.0028m³ per hour. 3 It is far below the relevant standards for leakage of breather valves at home and abroad, and has excellent high temperature resistance.

Description

Technical Field

[0001] This invention relates to the field of breathing valve sealing technology, specifically to a three-layer breathing valve composite diaphragm, its preparation method, and its application. Background Technology

[0002] A breather valve is a valve that ensures the storage tank is isolated from the atmosphere within a certain pressure range, while allowing it to breathe when the pressure exceeds or falls below this range. Its function is to prevent damage to the storage tank due to overpressure or vacuum, and to reduce evaporation losses of the stored medium. Installing a breather valve not only reduces gas emissions from the tank, thus lowering atmospheric pollution, but also prevents damage from overpressure or instability from excessive vacuum, contributing to both safety and environmental protection.

[0003] Currently, domestic research on breather valve design mainly focuses on gas flow above the opening pressure, while the gas leakage rate in the leakage range above and below the opening pressure (0.75 times the opening pressure) has not received sufficient attention. In fact, with the trend towards centralized and large-scale tank farms, this overlooked gas leakage could potentially lead to increased flammable gas concentrations within the tank farm, raising the risk of fire and explosion. Therefore, the American Petroleum Institute (API), in its breather valve standard API Std 2000, clearly stipulates that for breather valves with a nominal diameter less than 150 mm, the maximum leakage rate must not exceed 0.014 m³ / h. 3 For breather valves with a nominal diameter greater than 200mm, the maximum leakage rate per hour must not exceed 0.142m³. 3 The most stringent international standard for leakage control is the standard in some regions (of Germany) that requires breather valves with a nominal diameter of less than 150 mm to have a maximum leakage rate of no more than 0.0017 m³ / hour. 3 For breather valves with a nominal diameter greater than 200mm, the maximum leakage rate per hour must not exceed 0.0045m³. 3 Currently, domestic research and development of breather valves mainly focuses on mechanical structures. However, due to the repeated opening and closing of breather valves during use, coupled with the large amount of corrosive components in oil and gas, mechanical seals are easily damaged and fail, leading to increased leakage. Therefore, a reasonable mechanical structure combined with a high-efficiency sealing rubber diaphragm is necessary to achieve long-term low leakage in breather valves. However, limited by diaphragm materials, my country's breather valve industry standard SY / T0511-2010 stipulates that the maximum leakage rate per hour for breather valves with a nominal diameter of less than 150mm must not exceed 0.04m³. 3 For breather valves with a nominal diameter greater than 200mm, the maximum leakage rate must not exceed 0.4m³ per hour. 3The leakage volume was significantly higher than current international standards. This high leakage volume not only increases the safety risks of my country's petrochemical storage tank areas, posing a significant threat to people's peaceful lives, but also restricts my country's path towards domestically developed petrochemical oil and gas storage solutions. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem of high leakage and significant safety risks associated with traditional breather valve diaphragms (gaskets) used in large-nominal-diameter breather valves. This invention provides a three-layer composite breather valve diaphragm, its preparation method, and its application. By improving the performance of the composite fluororubber diaphragm, this invention can significantly reduce the leakage of breather valves for large-nominal-diameter storage tanks and exhibits excellent high-temperature resistance.

[0005] To achieve the above objectives, the present invention provides a three-layer breather valve composite diaphragm, the composite diaphragm comprising a polymer sheet layer, a fluororubber composite material layer, and a fiber composite polymer interlayer located between the polymer sheet layer and the fluororubber composite material layer, wherein the thickness of the polymer sheet layer is 0.1-1 mm; and the fluororubber composite material layer is made from a raw material composition containing fluororubber, inorganic filler, acid absorber, vulcanizing agent, release agent and colorant.

[0006] Preferably, the polymer sheet in the polymer layer is selected from one or more of polyetheretherketone, polytetrafluoroethylene and polyimide.

[0007] Preferably, the fiber composite polymer sheet forming the fiber composite polymer interlayer is selected from one or more of aramid polytetrafluoroethylene composite rubber, aramid polyimide rubber, glass fiber polyimide rubber, carbon fiber polyimide rubber and ceramic fiber polyimide rubber.

[0008] Preferably, the thickness of the fiber composite polymer interlayer is 0.1 to 0.5 mm.

[0009] Preferably, in the raw material composition, the fluororubber is type 26 fluororubber and / or type 246 fluororubber.

[0010] Preferably, in the raw material composition, the inorganic filler is selected from one or more of silica, calcium silicate, magnesium silicate, aluminum silicate, calcium carbonate, barium sulfate, diatomaceous earth, graphite, silicon nitride, and boron nitride.

[0011] Preferably, in the raw material composition, the acid absorbent is selected from one or more of magnesium oxide, calcium oxide, zinc oxide and calcium hydroxide.

[0012] Preferably, in the raw material composition, the vulcanizing agent is selected from one or more of N,N'-biscinnamaldehyde-1,6-hexanediamine, 2,2-(4-hydroxyphenyl)hexafluoropropane, dicumyl peroxide and 2,5-dimethyl-2,5-ditert-butylperoxide.

[0013] Preferably, in the raw material composition, the release agent is selected from one or more of zinc stearate, ammonium stearate, and paraffin wax.

[0014] Preferably, in the raw material composition, the colorant is selected from one or more of iron oxide red, colloidal graphite and carbon black.

[0015] Preferably, in the raw material composition, the weight ratio of the fluororubber, the inorganic filler, the acid absorber, the vulcanizing agent, the mold release agent and the colorant is 100:10-60:0.001-20:0.001-5:0.2-2:0.001-3.

[0016] Preferably, the raw material composition further contains a vulcanization accelerator.

[0017] Preferably, the weight ratio of the fluororubber to the vulcanization accelerator is 100:0.001 to 2.

[0018] Preferably, the vulcanization accelerator is selected from benzyltriphenylphosphine chloride and / or triallyl isocyanurate.

[0019] Preferably, the thickness ratio of the polymer sheet to the fluororubber composite layer is 1:1 to 4.

[0020] A second aspect of the present invention provides a method for making the three-layer breathing valve composite diaphragm, the method comprising:

[0021] (1) The raw material composition is mixed and then the resulting product is refined multiple times to obtain a fluororubber composite material.

[0022] (2) The fiber composite polymer sheet is placed between the polymer sheet and the fluororubber composite material, and then thermally bonded and vulcanized to obtain a composite film.

[0023] Preferably, in step (1), the mixing conditions include: a temperature of 50-80°C, a time of 15-60 min, and a rotation speed of 20-60 rpm.

[0024] Preferably, in step (1), the refining conditions include: a temperature of 100-140°C, a refining cycle of 10-30 times, and a roller gap of 0.2-4 mm.

[0025] Preferably, in step (2), the conditions for thermal bonding include: a temperature of 150-160°C and a time of 1-10 min.

[0026] Preferably, in step (2), the vulcanization conditions include a temperature of 180–240°C and a time of 8–24 hours.

[0027] A third aspect of the present invention provides a three-layer breather valve composite diaphragm prepared by the method described above.

[0028] The fourth aspect of the present invention provides a composite diaphragm as described above, or the application of the composite diaphragm as described above, as a sealing material for a breather valve.

[0029] The composite diaphragm provided by this invention comprises a polymer sheet layer of a specific thickness and a fluororubber composite material layer, and has a fiber composite polymer interlayer between the polymer sheet layer and the fluororubber composite material layer. The three-layer composite diaphragm with this feature has excellent yield deformation in the leakage range of the breather valve from above 0.75 times the opening pressure to below the opening pressure, thereby reducing the leakage of breather valves with large nominal diameters. At the same time, the breather valve composite diaphragm prepared by this invention has excellent high temperature resistance.

[0030] Furthermore, the leakage rate of the composite diaphragm provided by this invention at a temperature of 20°C and a breather valve opening pressure of 0.75 times is as low as 0.0010 m³ / hour for diaphragms used in breather valves with a nominal diameter of 150 mm or less. 3 The breather valve diaphragm, with a nominal diameter of 200mm, has a maximum leakage rate as low as 0.0028m³ per hour. 3 This is far below the relevant standards for leakage of breather valves both domestically and internationally. In this invention, the "nominal diameter" refers to the nominal diameter of the breather valve connecting flange. Attached Figure Description

[0031] Figure 1 This is a flowchart of the preparation of the three-layer breathing valve composite membrane according to the present invention. Detailed Implementation

[0032] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0033] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0034] The first aspect of the present invention provides a three-layer breather valve composite diaphragm, the composite diaphragm comprising a polymer sheet layer, a fluororubber composite material layer, and a fiber composite polymer interlayer located between the polymer sheet layer and the fluororubber composite material layer.

[0035] In this invention, the polymer sheet supports the composite diaphragm and is positioned on one side of the valve disc of the breather valve during use, preventing the diaphragm from sagging due to excessive softness and causing leakage. Lubricants and thermal conductive agents are added during the pretreatment of the polymer sheet, resulting in good lubricity, thermal conductivity, and anti-friction properties. The fluororubber composite layer has good elasticity and appropriate elastic deformation, and is positioned on one side of the valve seat of the breather valve during use, giving the breather valve excellent sealing performance. The fiber composite polymer interlayer in the middle helps maintain the dimensional stability of the composite diaphragm and increases its deformation recovery ability. Combining the polymer sheet, fiber composite polymer interlayer, and fluororubber composite layer can significantly reduce the leakage of breather valves with large nominal diameters and improve their high-temperature resistance.

[0036] In this invention, the thickness of the polymer sheet should be appropriate. If it is too thick, the membrane will be too hard overall and the surface will be uneven and concave, which will not achieve the effect of reducing the leakage of the breather valve.

[0037] In this invention, the thickness of the polymer sheet is 0.1–1 mm. In specific embodiments, the thickness of the polymer sheet can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1 mm.

[0038] In this invention, the polymer sheet refers to the material forming the polymer sheet layer. In specific embodiments, the polymer sheet forming the polymer sheet layer can be a material well known to those skilled in the art. In a preferred embodiment, the polymer sheet in the polymer sheet layer can be selected from one or more of polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), and polyimide (PI).

[0039] In a specific embodiment, the polymer sheet is entirely formed of polymer sheet material, and the polymer sheet material needs to be pretreated before use. The pretreatment includes: adding lubricant and thermal conductive agent to enhance its lubricity, thermal conductivity and anti-friction properties, and performing surface treatment on the polymer sheet material.

[0040] In this invention, specifically, the fiber composite polymer interlayer is formed of a fiber composite polymer sheet; the fiber composite polymer sheet refers to the material forming the fiber composite polymer interlayer. In specific embodiments of this invention, the fiber composite polymer sheet forming the fiber composite polymer interlayer can be a material well-known to those skilled in the art. In a preferred embodiment, the fiber composite polymer sheet forming the fiber composite polymer interlayer can be selected from one or more of aramid polytetrafluoroethylene composite rubber, aramid polyimide rubber, glass fiber polyimide rubber, carbon fiber polyimide rubber, and ceramic fiber polyimide rubber.

[0041] In a preferred embodiment, the thickness of the fiber composite polymer interlayer can be 0.1–0.5 mm. If the thickness of the fiber composite polymer interlayer is too large, the elasticity of the composite diaphragm will decrease significantly; if the thickness of the fiber composite polymer interlayer is too small, it will not be able to increase the deformation recovery effect; both excessive and insufficient thickness will affect the leakage of the breathing valve.

[0042] Through research, the inventors discovered that, in this invention, a composite membrane composed of a fluororubber composite material layer prepared from raw materials containing fluororubber, a fiber composite polymer interlayer, and the polymer sheet layer, as a sealing material for a breather valve, can significantly reduce the leakage of breather valves with large nominal diameters.

[0043] In this invention, the fluororubber composite material layer is made from a raw material composition containing fluororubber, inorganic filler, acid absorber, vulcanizing agent, release agent, and colorant. The fluororubber composite material layer is obtained by mixing, refining, thermally bonding, and vulcanizing the raw material composition.

[0044] In this invention, the fluororubber can be any fluororubber well-known in the art, as long as it can maintain the gasket shape and mechanical strength in oily, acidic, or alkaline environments. In a specific embodiment, the fluororubber in the raw material composition can be type 26 fluororubber and / or type 246 fluororubber.

[0045] In this invention, the inorganic filler can be a conventional choice in the art, as long as it can fill the rubber. In a preferred embodiment, in order to ensure that the diaphragm has good yield deformation in the leakage range above and below the opening pressure of the breather valve, and to further reduce the leakage of the breather valve, the inorganic filler in the raw material composition is selected from one or more of silica, calcium silicate, magnesium silicate, aluminum silicate, calcium carbonate, barium sulfate, diatomaceous earth, graphite, silicon nitride, and boron nitride.

[0046] In this invention, the acid absorber refers to an additive capable of absorbing acidic substances released during the rubber manufacturing process. The acid absorber can be a conventional choice in the art, as long as it can absorb the acidic substances released during rubber manufacturing. In a preferred embodiment, in the raw material composition, the acid absorber is selected from one or more of magnesium oxide, calcium oxide, zinc oxide, and calcium hydroxide.

[0047] In this invention, the vulcanizing agent can be a conventional choice in the art. In a specific embodiment, in the raw material composition, the vulcanizing agent is selected from one or more of N,N'-biscinnamaldehyde-1,6-hexanediamine, 2,2-(4-hydroxyphenyl)hexafluoropropane, dicumyl peroxide, and 2,5-dimethyl-2,5-di-tert-butylperoxide.

[0048] In this invention, the release agent can be a release agent well known to those skilled in the art. In a specific embodiment, in the raw material composition, the release agent is selected from one or more of zinc stearate, ammonium stearate, and paraffin wax.

[0049] In this invention, the colorant can be any colorant well-known to those skilled in the art, as long as it can color the composite film. In a specific embodiment, the colorant in the raw material composition is selected from one or more of iron oxide red, colloidal graphite, and carbon black.

[0050] In this invention, in order to improve the yield recovery performance of the fluororubber composite material layer and thereby reduce the leakage of the breather valve, it is necessary to reasonably control the amount of the fluororubber, the inorganic filler, the acid absorber, the vulcanizing agent, the release agent and the colorant.

[0051] In this invention, in a specific embodiment, the weight ratio of the fluororubber, the inorganic filler, the acid absorber, the vulcanizing agent, the mold release agent, and the colorant in the raw material composition can be 100:10-60:0.001-20:0.001-5:0.2-2:0.001-3, for example 100:10:0.28:0.15:1.89:1.54, or 100:60:0.5. 4:2.16:1.55:2.05, 100:20:10:2.5:1.6:2.5, 100:50:10.8:3.85:0.88:2.35, 100:30:0.2:0.1:1:1.5, 100:40:10.5:1.25:1.58:0.55, 100:10:0.2:0.1:1:1.5, 100:60:20:5:2:3.

[0052] In this invention, the addition of a vulcanization accelerator to the raw materials used to prepare the fluororubber composite layer is selected according to actual needs. In a specific embodiment, the raw material composition also contains a vulcanization accelerator. In a preferred embodiment, the weight ratio of the fluororubber to the vulcanization accelerator is 100:0.001 to 2, for example, 100:0.001, 100:0.1, 100:0.2, 100:0.5, 100:0.6, 100:0.7, 100:0.8, 100:0.9, or 100:1. Specifically, the vulcanization accelerator is selected from benzyltriphenylphosphine chloride and / or triallyl isocyanurate.

[0053] In this invention, to meet basic usage requirements, the thicknesses of the polymer sheet and the fluororubber composite layer need to satisfy a certain relationship. In specific embodiments, the thickness of the fluororubber composite layer is approximately equal to the thickness of the polymer sheet, or the thickness of the fluororubber composite layer is greater than that of the polymer sheet. In a preferred embodiment, the thickness ratio of the polymer sheet to the fluororubber composite layer is 1:1 to 4, for example, 1:1, 1:1.2, 1:1.4, 1:1.5, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.5, 1:2.6, 1:2.8, 1:3, 1:3.2, 1:3.4, 1:3.6, 1:3.8, or 1:4.

[0054] The second aspect of this invention provides a method for preparing the three-layer breather valve composite diaphragm described in the first aspect above, such as... Figure 1 As shown, the method includes:

[0055] (1) The raw material composition is mixed and then the resulting product is refined multiple times to obtain a fluororubber composite material.

[0056] (2) The fiber composite polymer sheet is placed between the polymer sheet and the fluororubber composite material, and then thermally bonded and vulcanized to obtain a composite film.

[0057] The method of the present invention first prepares a fluororubber composite material by mixing and refining, then places a fiber composite polymer sheet between the polymer sheet and the fluororubber composite material, and performs thermal bonding and vulcanization on the three to bond the fluororubber composite material, the fiber composite polymer sheet and the polymer sheet together to obtain a three-layer composite film including a polymer sheet layer, a fluororubber composite material layer, and a fiber composite polymer interlayer located between the polymer sheet layer and the fluororubber composite material layer.

[0058] In this invention, the mixing process can be performed according to conventional operations in the art. In a preferred embodiment, in step (1), the mixing temperature can be 50–80°C, for example, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C. In a preferred embodiment, in step (1), the mixing time can be 15–60 min, for example, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min. In a preferred embodiment, in step (1), the mixing speed can be 20–60 rpm, for example, 20 rpm, 25 rpm, 30 rpm, 35 rpm, 40 rpm, 45 rpm, 50 rpm, 55 rpm, or 60 rpm. In this invention, the mixing is performed using a Baisheng Company BL-6175-B model mixing machine.

[0059] In the method described in this invention, the refining process can be performed according to conventional operations in the art. In a preferred embodiment, in step (1), the refining temperature is 100–140°C, for example, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, or 140°C. In a preferred embodiment, in step (1), the number of refining cycles is 10, 15, 20, 25, or 30. In a preferred embodiment, the roller gap is 0.2–4 mm, for example, 0.2 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, or 4 mm. In this invention, the refining is performed using a Meissen Machinery MRM480 ​​mixing mill. In this invention, one refining cycle refers to the rollers rolling once over the mixed raw material.

[0060] In the method described in this invention, the thermal bonding can be a conventional choice in the art. In a preferred embodiment, in step (2), the thermal bonding temperature is 150–160°C, for example, 150°C, 151°C, 152°C, 153°C, 154°C, 155°C, 156°C, 157°C, 158°C, 159°C, or 160°C. In a preferred embodiment, in step (2), the thermal bonding time is 1–10 min, for example, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, or 10 min.

[0061] In the method described in this invention, the vulcanization process can be carried out according to conventional operations in the art. To ensure the diaphragm has good yield deformation in the leakage range above and below the breather valve's opening pressure (0.75 times the opening pressure), and to further reduce the breather valve leakage, the vulcanization conditions can be controlled within an appropriate range. In a preferred embodiment, in step (2), the vulcanization temperature can be 180–240°C, for example, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, or 240°C. In a preferred embodiment, in step (2), the vulcanization time is 8–24 hours, for example, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, or 24 hours.

[0062] In one specific embodiment, the method for preparing the three-layer breathing valve composite diaphragm includes the following steps:

[0063] (1) Preparation of fluororubber composite material: Fluororubber, inorganic filler, acid absorber, vulcanizing agent, release agent and colorant are mixed. The mixing temperature is 50-80℃, the time is 15-60min, and the rotation speed is 20-60 rpm. The weight ratio of the fluororubber, inorganic filler, acid absorber, vulcanizing agent, release agent and colorant is 100:10-60:0.001-20:0.001-5:0.2-2:0.001-3. Then the obtained product is refined 10-30 times. The refining temperature is 100-140℃ and the roller gap is 0.2-4mm to obtain fluororubber composite material.

[0064] (2) Preparation of composite membranes:

[0065] A fiber-reinforced polymer sheet with a thickness of 0.1–0.5 mm is placed between a polymer sheet with a thickness of 0.1–1 mm and the fluororubber composite material, and then thermally bonded at a temperature of 150–160°C for 1–10 min. Then, vulcanization is performed at a temperature of 180–240°C for 8–24 h to obtain a composite film.

[0066] In another specific embodiment, the method for preparing the three-layer breathing valve composite diaphragm includes the following steps:

[0067] (1) Preparation of fluororubber composite material: Fluororubber, inorganic filler, acid absorber, vulcanizing agent, release agent, colorant and vulcanization accelerator are mixed. The mixing temperature is 50-80℃, the time is 15-60min, and the rotation speed is 20-60 rpm. The weight ratio of the fluororubber, inorganic filler, acid absorber, vulcanizing agent, release agent and colorant is 100:10-60:0.001-20:0.001-5:0.2-2:0.001-3:0.001-2. Then the obtained product is refined 10-30 times. The refining temperature is 100-140℃ and the roller gap is 0.2-4mm to obtain fluororubber composite material.

[0068] (2) Preparation of composite membranes:

[0069] A fiber-reinforced polymer sheet with a thickness of 0.1–0.5 mm is placed between a polymer sheet with a thickness of 0.1–1 mm and the fluororubber composite material, and then thermally bonded at a temperature of 150–160°C for 1–10 min. Then, vulcanization is performed at a temperature of 180–240°C for 8–24 h to obtain a composite film.

[0070] A third aspect of this invention provides a super triple-layer breather valve composite diaphragm prepared by the method described above. The breather valve composite diaphragm prepared by the method of this invention has low valve leakage and good high-temperature resistance.

[0071] The fourth aspect of the present invention provides the application of the composite diaphragm described in the first aspect or the composite diaphragm described in the third aspect as a sealing material for a breather valve.

[0072] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto.

[0073] In this invention, the fluororubber 246 was purchased from LG Corporation of South Korea and has a density of 1.5 g / cm³. 3 Tensile strength 450 kg / cm 2 The fluororubber 26 was purchased from Shandong Huaxia Shenzhou Company, and its physical parameters are 1.8 g / cm³. 3 Tensile strength 135 kg / cm 2 .

[0074] In this invention, the aramid polytetrafluoroethylene composite rubber was purchased from Zhejiang Jusheng Fluorochemical Co., Ltd., with a density of 2.1 g / cm³. 3 The aramid polyimide rubber was purchased from Suzhou Yingchuan New Material Technology Co., Ltd., with a density of 1.9 g / cm³. 3 The glass fiber polyimide rubber was purchased from EMS, Switzerland, with a density of 1.4 g / cm³. 3The carbon fiber polyimide rubber was purchased from DowDuPont, with a density of 1.4 g / cm³. 3 The ceramic fiber polyimide rubber was purchased from ceramic fiber polyimide rubber suppliers, with a density of 1.42 g / cm³. 3 .

[0075] Example 1

[0076] (1) Preparation of fluororubber composite materials:

[0077] Fluororubber (10 kg of fluororubber 246), inorganic filler (6 kg of aluminum silicate), acid scavenger (1 kg of calcium oxide), vulcanizing agent (0.2 kg of N,N'-biscinnamaldehyde-1,6-hexanediamine), release agent (0.02 kg of zinc stearate), and colorant (0.3 kg of colloidal graphite) were added to a mixer and mixed at a speed of 60 rpm, a temperature of 60°C, and a time of 15 min. The resulting product was then refined 10 times with a roller gap of 0.2 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0078] (2) Preparation of composite membranes:

[0079] A 0.5 mm thick aramid polytetrafluoroethylene composite rubber sheet is placed on a 0.1 mm thick PEEK polymer sheet. Then, the fluororubber composite material is spread on the aramid polytetrafluoroethylene composite rubber sheet and thermally bonded at a temperature of 160°C for 1 minute to obtain a pre-cured composite film. The film is then vulcanized at 240°C for 8 hours to obtain a composite film A1 comprising a 0.2 mm fluororubber composite material layer, a 0.1 mm PEEK polymer sheet layer, and a 0.5 mm aramid polytetrafluoroethylene composite rubber interlayer located between the PEEK polymer sheet layer and the fluororubber composite material layer.

[0080] Example 2

[0081] (1) Preparation of fluororubber composite materials:

[0082] Fluororubber (10 kg of fluororubber 26), inorganic fillers (0.5 kg of silica, 0.3 kg of calcium silicate, 0.1 kg of magnesium silicate and 0.1 kg of boron nitride), acid scavenger (1 kg of magnesium oxide), vulcanizing agent (0.5 kg of N,N'-biscinnamaldehyde-1,6-hexanediamine), release agent (0.02 kg of paraffin wax), and colorant (0.2 kg of iron oxide red) were added to a mixer and mixed at a speed of 20 rpm, a temperature of 80°C, and a time of 60 min. The resulting product was then refined 20 times with a roller gap of 2 mm and a roller temperature of 100°C to obtain a fluororubber composite material.

[0083] (2) Preparation of composite membranes:

[0084] A 0.1 mm thick aramid polyimide rubber sheet is placed on a 0.5 mm thick PTFE polymer sheet. Then, the fluororubber composite material is spread on the aramid polyimide rubber sheet and thermally bonded at a temperature of 150°C for 10 minutes to obtain a pre-cured composite film. The film is then vulcanized at 180°C for 24 hours to obtain a composite film A2 comprising a 2 mm fluororubber composite layer, a 0.5 mm PTFE polymer sheet layer, and a 0.1 mm aramid polyimide rubber interlayer located between the PTFE polymer sheet layer and the fluororubber composite layer.

[0085] Example 3

[0086] (1) Preparation of fluororubber composite materials:

[0087] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of calcium carbonate, 1 kg of diatomaceous earth, 0.5 kg of calcium silicate, and 0.1 kg of graphite), acid scavenger (1 kg of zinc oxide), vulcanizing agent (0.02 kg of 2,2-(4-hydroxyphenyl)hexafluoropropane and 0.02 kg of benzyltriphenylphosphine chloride), release agent (0.02 kg of ammonium stearate), and colorant (0.03 kg of iron oxide red) were added to a mixer and mixed at a speed of 30 rpm, a temperature of 70°C, and a time of 40 min. The resulting product was then refined 30 times with a roller gap of 4 mm and a roller temperature of 120°C to obtain a fluororubber composite material.

[0088] (2) Preparation of composite membranes:

[0089] A 0.3 mm thick glass fiber polyimide rubber sheet is placed on a 1 mm thick PI polymer sheet, and then the fluororubber composite material is spread on the glass fiber polyimide rubber sheet and thermally bonded at a temperature of 150°C for 5 minutes to obtain a pre-cured composite film. The film is then vulcanized at 200°C for 16 hours to obtain a composite film A3 consisting of a 4 mm fluororubber composite layer, a 1 mm PI polymer sheet layer, and a 0.3 mm glass fiber polyimide rubber interlayer layer located between the PI polymer sheet layer and the fluororubber composite material layer.

[0090] Example 4

[0091] (1) Preparation of fluororubber composite materials:

[0092] Fluororubber (10 kg of fluororubber 26), inorganic fillers (4 kg of aluminum silicate, 1 kg of barium sulfate, 0.05 kg of silicon nitride and 0.2 kg of graphite), acid scavenger (1 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of dicumyl peroxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.02 kg of paraffin wax), and colorant (0.2 kg of iron oxide red) were added to a mixer and mixed at a speed of 40 rpm, a temperature of 65°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 0.5 mm and a roller temperature of 130°C to obtain a fluororubber composite material.

[0093] (2) Preparation of composite membranes:

[0094] A 0.3 mm thick carbon fiber polyimide rubber sheet is placed on a 0.6 mm thick PTFE polymer sheet. Then, the fluororubber composite material is spread on the carbon fiber polyimide rubber sheet and thermally bonded at a temperature of 160°C for 7 minutes to obtain a pre-cured composite film. The film is then vulcanized at 220°C for 12 hours to obtain a composite film A4 comprising a 0.6 mm fluororubber composite material layer, a 0.6 mm PTFE polymer sheet layer, and a 0.3 mm carbon fiber polyimide rubber interlayer located between the PTFE polymer sheet layer and the fluororubber composite material layer.

[0095] Example 5

[0096] (1) Preparation of fluororubber composite materials:

[0097] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of calcium silicate, 1 kg of magnesium silicate, 0.5 kg of calcium carbonate and 0.1 kg of graphite), acid scavenger (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0098] (2) Preparation of composite membranes:

[0099] A 0.4 mm thick ceramic fiber polyimide rubber sheet is placed on a 0.5 mm thick PTFE polymer sheet. Then, the fluororubber composite material is spread on the ceramic fiber polyimide rubber sheet and thermally bonded at a temperature of 160°C for 10 minutes to obtain a pre-cured composite film. The film is then vulcanized at 240°C for 16 hours to obtain a composite film A5 comprising a 2 mm fluororubber composite layer, a 0.5 mm PTFE polymer sheet layer, and a 0.4 mm ceramic fiber polyimide rubber interlayer located between the PTFE polymer sheet layer and the fluororubber composite layer.

[0100] Example 6

[0101] The method was implemented according to Example 5, except that the inorganic filler consisted of 0.5 kg of silica, 1 kg of silicon nitride, and 1.1 kg of boron nitride. The specific operation was as follows:

[0102] (1) Preparation of fluororubber composite materials:

[0103] Fluororubber (10 kg of fluororubber 246), inorganic fillers (0.5 kg of silica, 1 kg of silicon nitride and 1 kg of boron nitride), acid scavenger (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0104] (2) Preparation of composite membranes:

[0105] A 0.4 mm thick ceramic fiber polyimide rubber sheet is placed on a 0.5 mm thick PTFE polymer sheet. Then, the fluororubber composite material is spread on the ceramic fiber polyimide rubber sheet and thermally bonded at a temperature of 160°C for 10 minutes to obtain a pre-cured composite film. The film is then vulcanized at 240°C for 16 hours to obtain a composite film A6 comprising a 1 mm fluororubber composite layer, a 0.5 mm PTFE polymer sheet layer, and a 0.4 mm ceramic fiber polyimide rubber interlayer located between the PTFE polymer sheet layer and the fluororubber composite layer.

[0106] Example 7

[0107] The method was implemented according to Example 5, except that the inorganic filler consisted of 1 kg of aluminum silicate and 1.6 kg of diatomaceous earth. The specific operation was as follows:

[0108] (1) Preparation of fluororubber composite materials:

[0109] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of aluminum silicate and 1.6 kg of diatomaceous earth), acid absorbent (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0110] (2) Preparation of composite membranes:

[0111] A 0.4 mm thick ceramic fiber polyimide rubber sheet is placed on a 0.5 mm thick PTFE polymer sheet. Then, the fluororubber composite material is spread on the ceramic fiber polyimide rubber sheet and thermally bonded at a temperature of 160°C for 10 minutes to obtain a pre-cured composite film. The film is then vulcanized at 240°C for 16 hours to obtain a composite film A7 comprising a 1 mm fluororubber composite layer, a 0.5 mm PTFE polymer sheet layer, and a 0.4 mm ceramic fiber polyimide rubber interlayer located between the PTFE polymer sheet layer and the fluororubber composite layer.

[0112] Example 8

[0113] The method described in Example 5 was followed, except that no vulcanization accelerator was added. The specific operation was as follows:

[0114] (1) Preparation of fluororubber composite materials:

[0115] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of calcium silicate, 1 kg of magnesium silicate, 0.5 kg of calcium carbonate and 0.1 kg of graphite), acid scavenger (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0116] (2) Preparation of composite membranes:

[0117] A 0.4 mm thick ceramic fiber polyimide rubber sheet is placed on a 0.5 mm thick PTFE polymer sheet. Then, the fluororubber composite material is spread on the ceramic fiber polyimide rubber sheet and thermally bonded at a temperature of 160°C for 10 minutes to obtain a pre-cured composite film. The film is then vulcanized at 240°C for 16 hours to obtain a composite film A8 comprising a 1 mm fluororubber composite layer, a 0.5 mm PTFE polymer sheet layer, and a 0.4 mm ceramic fiber polyimide rubber interlayer located between the PTFE polymer sheet layer and the fluororubber composite layer.

[0118] Example 9

[0119] The method described in Example 5 is followed, except that the vulcanization temperature is 190°C. The specific operation is as follows:

[0120] (1) Preparation of fluororubber composite materials:

[0121] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of calcium silicate, 1 kg of magnesium silicate, 0.5 kg of calcium carbonate and 0.1 kg of graphite), acid scavenger (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0122] (2) Preparation of composite membranes:

[0123] A 0.4 mm thick ceramic fiber polyimide rubber sheet is placed on a 0.5 mm thick PTFE polymer sheet. Then, the fluororubber composite material is spread on the ceramic fiber polyimide rubber sheet and thermally bonded at a temperature of 160°C for 10 minutes to obtain a pre-cured composite film. The film is then vulcanized at 190°C for 16 hours to obtain a composite film A9 comprising a 1 mm fluororubber composite layer, a 0.5 mm PTFE polymer sheet layer, and a 0.4 mm ceramic fiber polyimide rubber interlayer located between the PTFE polymer sheet layer and the fluororubber composite layer.

[0124] Example 10

[0125] The method described in Example 5 was followed, except that the thickness of the PTFE polymer sheet was 0.8 mm. The specific operation was as follows:

[0126] (1) Preparation of fluororubber composite materials:

[0127] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of calcium silicate, 1 kg of magnesium silicate, 0.5 kg of calcium carbonate and 0.1 kg of graphite), acid scavenger (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0128] (2) Preparation of composite membranes:

[0129] A 0.4 mm thick ceramic fiber polyimide rubber sheet is placed on a 0.8 mm thick PTFE polymer sheet. Then, the fluororubber composite material is spread on the ceramic fiber polyimide rubber sheet and thermally bonded at a temperature of 160°C for 10 minutes to obtain a pre-cured composite film. The film is then vulcanized at 240°C for 16 hours to obtain a composite film A10 comprising a 1 mm fluororubber composite layer, a 0.8 mm PTFE polymer sheet layer, and a 0.4 mm ceramic fiber polyimide rubber interlayer located between the PTFE polymer sheet layer and the fluororubber composite layer.

[0130] Comparative Example 1

[0131] The method described in Example 5 was followed, except that the thickness of the PTFE polymer sheet was 1.5 mm. The specific operation was as follows:

[0132] (1) Preparation of fluororubber composite materials:

[0133] Fluororubber (10 kg of fluororubber 246), inorganic fillers (1 kg of calcium silicate, 1 kg of magnesium silicate, 0.5 kg of calcium carbonate and 0.1 kg of graphite), acid scavenger (0.5 kg of calcium oxide and 0.5 kg of calcium hydroxide), vulcanizing agent (0.01 kg of 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg of triallyl isocyanurate), release agent (0.01 kg of paraffin wax), and colorant (0.15 kg of iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0134] (2) Preparation of composite membranes:

[0135] A 0.4 mm thick ceramic fiber polyimide rubber sheet is placed on a 1.5 mm thick PTFE polymer sheet. Then, the fluororubber composite material is spread on the ceramic fiber polyimide rubber sheet and thermally bonded at a temperature of 160°C for 10 minutes to obtain a pre-cured composite film. The film is then vulcanized at 240°C for 16 hours to obtain composite film B1, which includes a 1 mm fluororubber composite material layer, a 1.5 mm PTFE polymer sheet layer, and a 0.4 mm ceramic fiber polyimide rubber interlayer located between the PTFE polymer sheet layer and the fluororubber composite material layer.

[0136] Comparative Example 2

[0137] The method described in Example 5 was followed, except that nitrile rubber (purchased from LG Corporation, Korea, grade LG B3250) was used instead of fluororubber. The specific operation was as follows:

[0138] (1) Preparation of nitrile rubber composite material:

[0139] Nitrile rubber (10 kg), inorganic fillers (1 kg calcium silicate, 1 kg magnesium silicate, 0.5 kg calcium carbonate and 0.1 kg graphite), acid scavenger (0.5 kg calcium oxide and 0.5 kg calcium hydroxide), vulcanizing agent (0.01 kg 2,5-dimethyl-2,5-di-tert-butylperoxide), vulcanization accelerator (0.01 kg triallyl isocyanurate), release agent (0.01 kg paraffin wax), and colorant (0.15 kg iron oxide red) were added to a mixer and mixed at a speed of 50 rpm, a temperature of 70°C, and a time of 30 min. The resulting product was then refined 30 times with a roller gap of 1 mm and a roller temperature of 140°C to obtain a nitrile rubber composite material.

[0140] (2) Preparation of composite membranes:

[0141] A 0.4 mm thick ceramic fiber polyimide rubber sheet is placed on a 0.5 mm thick PTFE polymer sheet. Then, the nitrile rubber composite material is spread on the ceramic fiber polyimide rubber sheet and thermally bonded at a temperature of 160°C for 10 minutes to obtain a pre-cured composite film. The film is then vulcanized at 240°C for 16 hours to obtain composite film B2, which includes a 2 mm nitrile rubber composite material layer, a 0.5 mm PTFE polymer sheet layer, and a 0.4 mm ceramic fiber polyimide rubber interlayer located between the PTFE polymer sheet layer and the nitrile rubber composite material layer.

[0142] Comparative Example 3

[0143] The method was implemented according to Example 1, except that instead of using a 0.5 mm thick aramid polytetrafluoroethylene composite rubber sheet, the fluororubber composite material was directly vulcanized with the PEEK polymer sheet.

[0144] (1) Preparation of fluororubber composite materials:

[0145] Fluororubber (10 kg of fluororubber 246), inorganic filler (6 kg of aluminum silicate), acid scavenger (1 kg of calcium oxide), vulcanizing agent (0.2 kg of N,N'-biscinnamaldehyde-1,6-hexanediamine), release agent (0.02 kg of zinc stearate), and colorant (0.3 kg of colloidal graphite) were added to a mixer and mixed at a speed of 60 rpm, a temperature of 60°C, and a time of 15 min. The resulting product was then refined 10 times with a roller gap of 0.2 mm and a roller temperature of 140°C to obtain a fluororubber composite material.

[0146] (2) Preparation of composite membranes:

[0147] Fluororubber composite material was spread on a 0.1 mm thick PEEK polymer sheet and thermally bonded at a temperature of 160 °C for 1 min to obtain a pre-cured composite film. The film was then vulcanized at 240 °C for 8 h to obtain composite film B3 consisting of a 0.2 mm fluororubber composite material layer and a 0.1 mm PEEK polymer sheet layer.

[0148] Comparative Example 4

[0149] The method was implemented according to Example 2, except that instead of using a 0.1 mm thick aramid polyimide rubber sheet, the fluororubber composite material was directly vulcanized with the PEEK polymer sheet.

[0150] (1) Preparation of fluororubber composite materials:

[0151] Fluororubber (10 kg of fluororubber 26), inorganic fillers (0.5 kg of silica, 0.3 kg of calcium silicate, 0.1 kg of magnesium silicate and 0.1 kg of boron nitride), acid scavenger (1 kg of magnesium oxide), vulcanizing agent (0.5 kg of N,N'-biscinnamaldehyde-1,6-hexanediamine), release agent (0.02 kg of paraffin wax), and colorant (0.2 kg of iron oxide red) were added to a mixer and mixed at a speed of 20 rpm, a temperature of 80°C, and a time of 60 min. The resulting product was then refined 20 times with a roller gap of 2 mm and a roller temperature of 100°C to obtain a fluororubber composite material.

[0152] (2) Preparation of composite membranes:

[0153] Fluororubber composite material is laid on a 0.5 mm thick PTFE polymer sheet and thermally bonded at a temperature of 150 °C for 10 min to obtain a pre-cured composite film. The film is then vulcanized at 180 °C for 24 h to obtain a composite film B4 consisting of a 2 mm fluororubber composite material layer and a 0.5 mm PTFE polymer sheet layer.

[0154] Test Example 1

[0155] The maximum leakage of the composite membranes prepared in the test examples and comparative examples is shown in Table 1. The maximum leakage was determined according to the following method:

[0156] The composite membranes A1-A10 and B1-B4 prepared in Examples 1-10 and Comparative Examples 1-4 were cut after being left to stand to obtain membranes 1a-10a, B1a, B2a, B3a, and B4a that match a breathing valve with a nominal diameter of 150 mm, and membranes 1b-10b, B1b, B2b, B3b, and B4b that match a breathing valve with a nominal diameter of 200 mm. The tank was left to stand for 24 hours at 20℃ and 60% humidity. The leakage test was conducted according to SY / T0511-2010 8.6. The specific procedure was as follows: the composite diaphragm was installed on the valve disc of the breather valve with different nominal diameters. The valve disc counterweight was 1350Pa. The breather valve was then installed on the breather valve test platform. The pressure was adjusted to 1012Pa (0.75 times the opening pressure). The leakage of the breather valve was measured. The value was recorded once every minute for a total of three times. The arithmetic mean was taken as the leakage of the tank breather valve when the pressure was not lower than 0.75 times the opening pressure (1012Pa).

[0157] Table 1

[0158]

[0159]

[0160] Test Example 2

[0161] The high-temperature resistance of the composite films prepared in Examples 1 and 2 and Comparative Examples 3 and 4 was tested, and the results are shown in Table 2. The high-temperature resistance was determined using the following methods:

[0162] According to GB / T 528-2009, composite films A1 and A2 prepared in Examples 1 and 2, and composite films B3 and B4 prepared in Comparative Examples 3 and 4 were cut into several type 2 dumbbell specimens. The four types of specimens were placed in air ovens at 80℃, 100℃, and 120℃ respectively, and heated continuously for 48 hours, 96 hours, and 168 hours, respectively. Their tensile strength, rate of change of tensile strength, elongation at break, and rate of change of elongation at break were tested.

[0163] Table 2

[0164]

[0165]

[0166] As can be seen from Table 1, the breathing valve composite diaphragm prepared according to the method of the examples has a low leakage rate; in Comparative Example 1, the PTFE polymer sheet is too thick, and the leakage rate of the breathing valve increases significantly; in Comparative Example 2, replacing nitrile rubber with fluororubber significantly increases the leakage rate of the breathing valve; in Comparative Examples 3 and 4, the fiber composite polymer sheet is not used, and the leakage rate of the breathing valve is comparable to that of the examples.

[0167] As can be seen from the results in Table 2, the tensile strength of the composite films prepared in Examples 1-2 decreased from a maximum of 12.5 N / mm² during the heating process at temperatures of 80℃ to 120℃ for 48h to 168h. 2 Reduced to a minimum of 11.0 N / mm 2 The tensile strength change rate was 0–11.3%, and the elongation at break increased from 216% to a maximum of 240%, while the elongation at break change rate increased from 0 to a maximum of 11.1%. In Comparative Examples 3-4, the composite films prepared at temperatures of 80℃–120℃ for continuous heating for 48h–168h showed a tensile strength increase from a maximum of 9.7 N / mm². 2 Reduced to a minimum of 6.3 N / mm 2 The tensile strength variation rate was 1.0%–25.3%, and the elongation at break increased from 234% to a maximum of 292%, with the elongation at break variation rate increasing from 0.4% to a maximum of 25.3%. It is evident that, under high-temperature conditions, the composite membranes prepared in Examples 1-2 exhibit higher tensile strength and lower elongation at break compared to the composite membranes prepared in Comparative Examples 3-4. In other words, the composite membranes prepared in these examples demonstrate better high-temperature resistance than those prepared in Comparative Examples 3 and 4.

[0168] It is evident that the composite diaphragm obtained by adopting the technical solution described in this invention significantly reduces the leakage of the breather valve from 0.75 times the opening pressure to below the opening pressure, and also exhibits excellent high-temperature resistance.

[0169] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A three-layer breather valve composite diaphragm, characterized in that, The composite membrane comprises a polymer sheet, a fluororubber composite material layer, and a fiber composite polymer interlayer located between the polymer sheet and the fluororubber composite material layer. The thickness of the polymer sheet is 0.1~1mm; The thickness of the fiber composite polymer interlayer is 0.1~0.5mm; The thickness ratio of the polymer sheet to the fluororubber composite layer is 1:1 to 4; The fluororubber composite material layer is made from a raw material composition containing fluororubber, inorganic filler, acid absorber, vulcanizing agent, release agent and colorant.

2. The three-layer breather valve composite diaphragm according to claim 1, characterized in that, The polymer sheet forming the polymer layer is selected from one or more of polyetheretherketone, polytetrafluoroethylene, and polyimide.

3. The three-layer breather valve composite diaphragm according to claim 1 or 2, characterized in that, The fiber composite polymer sheet forming the fiber composite polymer interlayer is selected from one or more of aramid polytetrafluoroethylene composite rubber, aramid polyimide rubber, glass fiber polyimide rubber, carbon fiber polyimide rubber and ceramic fiber polyimide rubber.

4. The three-layer breather valve composite diaphragm according to claim 1 or 2, characterized in that, In the raw material composition, the fluororubber is type 26 fluororubber and / or type 246 fluororubber.

5. The three-layer breather valve composite diaphragm according to claim 1, characterized in that, In the raw material composition, the inorganic filler is selected from one or more of the following: silica, calcium silicate, magnesium silicate, aluminum silicate, calcium carbonate, barium sulfate, diatomaceous earth, graphite, silicon nitride, and boron nitride.

6. The three-layer breather valve composite diaphragm according to claim 1, characterized in that, In the raw material composition, the acid absorbent is selected from one or more of magnesium oxide, calcium oxide, zinc oxide and calcium hydroxide.

7. The three-layer breather valve composite diaphragm according to claim 1, characterized in that, In the raw material composition, the vulcanizing agent is selected from one or more of N,N'-biscinnamaldehyde-1,6-hexanediamine, 2,2-(4-hydroxyphenyl)hexafluoropropane, dicumyl peroxide and 2,5-dimethyl-2,5-ditert-butylperoxide.

8. The three-layer breather valve composite diaphragm according to claim 1, characterized in that, In the raw material composition, the release agent is selected from one or more of zinc stearate, ammonium stearate and paraffin wax.

9. The three-layer breather valve composite diaphragm according to claim 1, characterized in that, In the raw material composition, the colorant is selected from one or more of iron oxide red, colloidal graphite and carbon black.

10. The three-layer breather valve composite diaphragm according to claim 1 or 2, characterized in that, In the raw material composition, the weight ratio of the fluororubber, the inorganic filler, the acid absorber, the vulcanizing agent, the mold release agent and the colorant is 100:10~60:0.001~20:0.001~5:0.2~2:0.001~3.

11. The three-layer breather valve composite diaphragm according to claim 1, characterized in that, The raw material composition also contains a vulcanization accelerator.

12. The three-layer breather valve composite diaphragm according to claim 11, characterized in that, The weight ratio of the fluororubber to the vulcanization accelerator is 100:0.001~2.

13. The three-layer breather valve composite diaphragm according to claim 11 or 12, characterized in that, The vulcanization accelerator is selected from benzyltriphenylphosphine chloride and / or triallyl isocyanurate.

14. A method for preparing the three-layer breathing valve composite diaphragm according to any one of claims 1-13, characterized in that, The method includes: (1) The raw material composition is mixed and then the resulting product is refined multiple times to obtain a fluororubber composite material; (2) Place the fiber composite polymer sheet between the polymer sheet and the fluororubber composite material, and then perform thermal bonding and vulcanization to obtain a composite film.

15. The method according to claim 14, characterized in that, In step (1), the mixing conditions include: temperature of 50~80℃, time of 15~60min, and rotation speed of 20~60 rpm.

16. The method according to claim 14 or 15, characterized in that, In step (1), the refining conditions include: a temperature of 100~140℃, a refining cycle of 10~30 times, and a roller gap of 0.2~4mm.

17. The method according to claim 14, characterized in that, In step (2), the conditions for thermal bonding include: a temperature of 150~160℃ and a time of 1~10min.

18. The method according to claim 14, characterized in that, In step (2), the vulcanization conditions include a temperature of 180~240℃ and a time of 8~24h.

19. A three-layer breathing valve composite diaphragm prepared by the method according to any one of claims 14-18.

20. The use of the three-layer breather valve composite diaphragm according to any one of claims 1-13 or the three-layer breather valve composite diaphragm according to claim 19 as a breather valve sealing material.

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